According to the circuit structure, commonly used electric vehicle chargers can be roughly divided into single -pipe switching power supply with the UC3842 driver field effect tube. With the LM358 dual transportation, the three -stage charging method is used. The control chip controls the TL494 as the core to promote 2 13007 high -voltage triode.Common faults of chargers include: high -pressure faults, low -pressure failures, high pressure, and low pressure. There are three categories of failure.Let ’s introduce the knowledge of electric bicycle charger!
Working principle of electric vehicle charger
The 220V AC power through the T0 two -way filtering inhibitory interference. The rectification of the D1 is the pulse DC, and then the C11 is filtered to form a stable 300V DC power.U1 is a TL3842 pulse width modulation integrated circuit.Its 5 feet are the negative electrode of the power supply, the 7 -pin is the positive pole of the power supply, and the 6 -pin is the pulse output direct drive field effect tube Q1 (K1358).Essence2 feet are voltage feedback, which can adjust the output voltage of the charger.4 oscillating resistance R1, and oscillating capacitance C1.T1 is a high -frequency pulse transformer, with three effects.The first is to press the high -voltage pulse to be pressed into a low -voltage pulse.The second is to play a role in isolation and high pressure to prevent electric shock.The third is to provide working power supply for UC3842.D4 is a high -frequency rectification (16A60V) C10 is a low -voltage filter capacitor, D5 is 12V voltage diode, and U3 (TL431) is the precision reference voltage source. With the U2 (optocoupler 4n35), it can automatically adjust the voltage of the charger.Adjust the W2 (fine -tuning resistor) to the voltage of the charger finely.D10 is a power indicator.D6 is the charging indicator.The R27 is a current-current-taking resistor (0.1 ohm, 5W) to change the resistance value of W1 to adjust the turning point current (200-300 mA) of the charger rotation.At the beginning of the power, there is a voltage of about 300V on the C11.
This voltage is loaded to Q1 through T1.The second road passed R5, C8, C3, reaching the seventh pin of U1.Forced U1 to start.U1s 6 -pin output square wave pulse, Q1 work, current passes R25 to the ground.At the same time, the T1 sub -coil generates an induction voltage. After D3, R12 provides U1 with a reliable power supply.The voltage of the T1 output coil has a stable voltage through D4 and C10 rectifier filtering.This voltage is charged to the battery through D7 (D7 to prevent the battery from pouring the batterys current).The second road passed the R14, D5, C9, and provided 12V working power supply for LM358 (dual transport calculation amplifier, 1 pin as power supply, 8 feet) and its peripheral circuit.D9 provides a reference voltage for LM358, with R26 and R4 division reaching the second and fifth foot of LM358.When charging normally, the upper end of the R27 has a voltage of 1.15-0.18V. The voltage is added to the third foot of the LM358 through the R17, and a high voltage is sent out from the 1 foot.This voltage is all the way through R18, forced Q2 to be turned on, D6 (red light) is lit, the second road is injected into the LM358 6 pin, the 7 -pin output low voltage, forcing the Q3 to turn off, the D10 (green light) goes off, the charger enters the constant current flow into the constant current flow,Charging phase.
When the battery voltage rises to about 44.2V, the charger enters the constant voltage charging phase, the output voltage is maintained at about 44.2V, the charger enters the constant voltage charging phase, and the current gradually decreases.When the charging current decreases to 200mA -300mA, the voltage at the upper end of the R27 decreases, the 3 -pin voltage of the LM358 is lower than 2, and the output of 1 foot outputs low voltage, Q2 is off, D6 is extinguished.At the same time, the 7 -pin output high voltage, this voltage all the way to Q3, D10 lights up.On the other way, the W1 reaches the feedback circuit to reduce the voltage.The charger enters the trick charging stage.After 1-2 hours, the charging is over.
Common faults of electric vehicle charging equipment
There are three common faults for chargers: 1. High -pressure faults 2. Low pressure failure 3. High pressure, low pressure faults.
The main phenomenon of high -voltage failure is that the indicator light is not bright, its features are fuses melting, rectifier diode D1 breaks out, capacitor C11 drum bag or bursts.Q1 breakdown, R25 opens the way.U1s 7 -footed ground is short -circuited.R5 opens the road, U1 has no start voltage.Replace the above components to repair.If the 7 -pin of U1 has a voltage of more than 11V and the 8 -pin has 5V voltage, it means that U1 is basically normal.The pins of Q1 and T1 should be focused on whether there are virtual welding.If Q1 is continuously penetrated, and Q1 is not hot, it is usually D2 and C4 fails. If Q1 is penetrated and hot, generally the low voltage part has leakage or short circuit, excessive or UC3842s 6 -pin output pulse waveform is abnormal, Q1 Q1The switching loss and heat increase greatly increased, causing Q1 to be excessive and burned.Other phenomena of high -voltage faults are flickering, and the output voltage is low and unstable. Generally, the pin of T1 has virtual welding, or D3, R12 open roads, TL3842 and its peripheral circuits have no working power supply.Another rare high -voltage failure is that the output voltage is higher than 120V. Generally, the U2 fails. The R13 road or U3 breaks down the 2 pin voltage of the U1, and the 6 -footed ultra -width pulse is sent.At this time, it cannot be powered on for a long time, otherwise the low -voltage circuit will be severely burned.Most of the low -voltage faults are reversed with the positive and negative pole of the charger and the battery, which causes R27 to burn and LM358 penetrate.The phenomenon is that the red light has been on, the green light is not on, the output voltage is low, or the output voltage is close to 0V. Replace the above components to repair it.In addition, the W2 is drifting due to jitter and output voltage. If the output voltage is high, the battery will be overwhelmed, severely lost water, hot, and eventually leads to heat out of control and burst battery.If the output voltage is low, the battery will owe.When there are faults at high and low voltage circuits, first comprehensively detect all diodes, triode, optocoupler 4n35, field effect tube, electrolytic capacitance, integrated circuit, R25, R5, R27, especially D4 (16A60V, fast, fastRestore the diode), C10 (63V, 470UF).Avoid blindly expanding the range of faults.
How to judge the quality of the charger
A good electric vehicle charger uses positive and negative pulse technology to effectively prevent, suppress, and eliminate the vulcanization and polarization of batteries.It can keep the capacity of new batteries stable for a long time; to restore the capacity of the old battery with polarization and decreased capacity, and effectively extend the service life of the battery by 2 to 3 times.It has functions such as intelligent timing protection function, automatic temperature compensation function, instant impact protection of the power grid, and super -strong moisture anti -corrosion.

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